The object of the present invention is an improved device for controlling the functions of an electronic watch.
Current electronic watches, particularly those provided with a numeric display, often are equipped with numerous functions as, for example, synchronization, multiple alarm, time zones and the like.
These different functions may be controlled by means of one or several push-buttons arranged on the periphery of the watch and incorporated in the thickness of the watch, and which act mechanically on an electric contact placed on the electronic module located in the case.
These push-buttons pose technological problems which are difficult to solve because of the requirements which respect to leaktightness, reliability and price, especially if they must fit into very thin watches.
Devices also are known which carry out the role of electronic switches based on the principle of the detection either of a change in capacity or of a change in resistance when the user places his finger on a predetermined spot on the glass or the case of the watch.
The disadvantage of a device with capacitive action is that it consumes a great deal of energy. In fact, the capacitive divider containing the capacity which can be varied according to the position of the finger must constantly have an alternating current flowing through it.
A system with resistive action presents the disadvantage, in addition to great energy consumption, of being particularly sensitive to dirt adhering to the surface of the case. It is thus difficult to ensure that this device will function correctly.
Besides, these two later types of device pose very great aesthetic and technological problems in the construction of the case. As a matter of fact, the contact surfaces adapted to the finger and the electrical connections to the electronic module must be combined, to allow for the requirements of leaktightness and reliability and utilization of the available surface.